The invention relates in general to a toolholder assembly with an insert for cutting a workpiece and, in particular, to a toolholder assembly with an internal coolant deliver system to permit effective coolant delivery to an interface between the cutting area of the cutting insert and the workpiece.
Metal cutting tools for performing metal working operations generally comprise a cutting insert having a surface terminating at a cutting edge and a toolholder formed with a seat adapted to receive the insert. The cutting insert engages a workpiece and removes a chip therefrom. Obviously, it is desirable to lengthen the life of a cutting insert in metal cutting operations. Longer insert life leads to lower operating costs and better machine efficiency. One factor in the life of a cutting insert is the temperature of the insert during cutting operations. A higher insert temperature will result in a shorter useful life of an insert.
Many systems have been designed to lower the insert temperature during cutting. For example, coolants may be generally applied through nozzles directed at the cutting edge of the insert. The coolant contacting the chip serves not only to lower the temperature of the insert, but also to remove the chip from the cutting area. The farther the distance of the nozzle to the cutting edge, the more likely the chip will block the coolant from reaching the cutting area. The nozzles are often a distance of 1-12 inches away from the cutting edge. This is too far of a distance for effective cooling. The farther the coolant must be sprayed the more the coolant will mix with air and the less likely it will be to actually contact the tool-chip interface.
Some have improved cooling by directing high pressure and high volume coolant at the cutting edge. Others have designed grooves between the insert and a top plate that secures the insert in the holder to reduce the distance the coolant must be sprayed. Some have delivered liquid nitrogen as the coolant relatively near the cutting edge of an insert. Each variation has shown limited effectiveness. Many still are positioned to far from the tool-workpiece interface. Those with grooves between the top plate and the insert get fluid closer to the tool-workpiece interface, but are not close enough. Some designs are also limited in that the direction of fluid flow is almost completely limited to one plane. The liquid nitrogen systems have shown some benefit, but is cost prohibitive for most applications. It is clear there remains a need for a simple and effective assembly for insert cooling during metal cutting operations.